U.S. patent number 7,927,897 [Application Number 12/327,215] was granted by the patent office on 2011-04-19 for photoresist composition and method of manufacturing array substrate using the same.
This patent grant is currently assigned to AZ Electronic Materials (Japan) K.K., Samsung Electronics Co., Ltd.. Invention is credited to Jae-Young Choi, Deok-Man Kang, Hi-Kuk Lee, Min-Soo Lee, Sae-Tae Oh, Sang-Hyun Yun.
United States Patent |
7,927,897 |
Lee , et al. |
April 19, 2011 |
Photoresist composition and method of manufacturing array substrate
using the same
Abstract
A photoresist composition includes a binder resin, a photo acid
generator, an acryl resin having four different types of monomers,
and a solvent.
Inventors: |
Lee; Hi-Kuk (Yongin-si,
KR), Yun; Sang-Hyun (Suwon-si, KR), Lee;
Min-Soo (Hwaseong-si, KR), Kang; Deok-Man
(Seongnam-si, KR), Oh; Sae-Tae (Pyeongtaek-si,
KR), Choi; Jae-Young (Suwon-si, KR) |
Assignee: |
Samsung Electronics Co., Ltd.
(Suwon-si, KR)
AZ Electronic Materials (Japan) K.K. (Tokyo,
JP)
|
Family
ID: |
40998726 |
Appl.
No.: |
12/327,215 |
Filed: |
December 3, 2008 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20090215233 A1 |
Aug 27, 2009 |
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Foreign Application Priority Data
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Feb 26, 2008 [KR] |
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10-2008-0017354 |
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Current U.S.
Class: |
438/29;
257/E33.074; 257/E21.223; 438/694; 257/E21.599; 257/E21.257;
257/E21.232 |
Current CPC
Class: |
H01L
27/1214 (20130101); H01L 27/1288 (20130101); G03F
7/0233 (20130101) |
Current International
Class: |
H01L
21/00 (20060101) |
Field of
Search: |
;438/29,694
;257/21.223,232,257,599,33.074 ;430/270.1,280.1,326
;526/266,270,280,282 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2001033951 |
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Feb 2001 |
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JP |
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2003342434 |
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Dec 2003 |
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JP |
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1020010040651 |
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May 2001 |
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KR |
|
Primary Examiner: Lebentritt; Michael S
Attorney, Agent or Firm: H.C. Park & Associates, PLC
Claims
What is claimed is:
1. A method of manufacturing an array substrate, comprising:
forming a gate line and a gate electrode on a base substrate;
forming a gate insulation layer, an active layer, and a data metal
layer on the base substrate formed the gate line and the gate
electrode; forming a photoresist film using a photoresist
composition comprising a binder resin, a photo acid generator, an
acryl resin represented by Chemical Formula 1, and a solvent, the
photoresist film formed on the data metal layer; forming a first
photoresist pattern by patterning the photoresist film, the first
photoresist pattern comprising a source electrode/line portion
having a first thickness, a drain electrode portion having the
first thickness, and a channel forming portion having a second
thickness; forming a data line and a channel portion by etching the
data metal layer and the active layer using the first photoresist
pattern as a mask; forming a second photoresist pattern by removing
the channel forming portion of the first photoresist pattern, the
second photoresist pattern exposing a portion of the data metal
layer; forming a source electrode and a drain electrode by etching
the data metal layer using the second photoresist pattern as a
mask; and forming an ohmic contact pattern by etching the active
layer using the second photoresist pattern as a mask, ##STR00008##
wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, and R.sub.5 each
represent a hydrogen atom or an alkyl group having 1-4 carbon
atoms, and a, b, d, and e each represent a value in a range of
about 0.01 to about 0.99, and the sum of a, b, d, and e is 1.
2. The method of claim 1, wherein a is about 0.5 to about 0.6, b is
about 0.25 to about 0.35, d is about 0.05 to about 0.15, and e is
about 0.01 to about 0.1.
3. The method of claim 2, wherein the acryl resin is represented by
Chemical Formula 2, ##STR00009##
4. The method of claim 1, further comprising a hydroxyl phenol
derivative represented by Chemical Formula 3, ##STR00010## wherein
R.sub.6, R.sub.7, and R.sub.8 each represent an alkyl group having
1-3 carbon atoms.
5. The method of claim 4, wherein R.sub.6, R.sub.7, and R.sub.8
each represent a methyl group.
6. The method of claim 1, wherein a weight average molecular weight
of the acryl resin is about 5,000 to about 30,000.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority from and the benefit of Korean
Patent Application No. 10-2008-0017354, filed on Feb. 26, 2008,
which is hereby incorporated by reference for all purposes as if
fully set forth herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photoresist composition and a
method of manufacturing an array substrate including the same. More
particularly, the present invention relates to a photoresist
composition used in a photolithography process to manufacture an
array substrate and a method of manufacturing the array
substrate.
2. Discussion of the Background
Generally, a liquid crystal display (LCD) panel includes a display
substrate having a thin-film transistor (TFT) as a switching device
driving a pixel, an opposite substrate opposite the display
substrate, and a liquid crystal layer between the display substrate
and the opposite substrate. The light transmittance of liquid
crystal included in the LCD panel may be altered by changing a
voltage applied thereto so that the LCD panel may display an
image.
The display substrate may be formed by a photolithography process
using a photoresist composition. Typically, the photolithography
process is a four-mask process, which uses four masks for etching
processes, so that the method of manufacturing the display
substrate may be simple.
The exposure device used in the photolithography process may
include an optical system, and the focus of the optical system
depends on a distance between the optical system and a substrate.
Thus, maintaining a constant distance between the optical system
and the substrate is important. When the distance between the
optical system and the substrate changes, the intensity of
radiation (light energy) changes. When the intensity differs from
that specified by a user, it may not be possible to form a fine
photoresist pattern on the substrate.
The photoresist pattern may not be reliably patterned due to
physical factors such as the manufacturing precision of a stage
supporting the substrate, vibrations when transferring the
substrate, manufacturing errors in the optical system of the
exposure device, etc. Furthermore, an increased substrate size may
decrease the overall reliability of the photoresist patterning.
SUMMARY OF THE INVENTION
The present invention provides a photoresist composition that may
improve the exposure margins and thermal resistance of a
photoresist pattern including the photoresist composition.
The present invention also provides a method of manufacturing an
array substrate including the photoresist composition.
Additional features of the invention will be set forth in the
description which follows, and in part will be apparent from the
description, or may be learned by practice of the invention.
The present invention discloses a photoresist composition including
a binder resin, a photo acid generator, an acryl resin represented
by Chemical Formula 1, and a solvent.
##STR00001##
In Chemical Formula 1, R.sub.1, R.sub.2, R.sub.3, R.sub.4, and
R.sub.5 each represent a hydrogen atom or an alkyl group having 1-4
carbon atoms, and a, b, d, and e each represent a value in a range
of 0.01 to 0.99, and the sum of a, b, d and e is 1.
The present invention also discloses a method of manufacturing an
array substrate. A gate line and a gate electrode are formed on a
base substrate. A gate insulation layer, an active layer, and a
source metal layer are formed on the base substrate having the gate
line and the gate electrode. A photoresist film is formed by
depositing the above described photoresist composition on the
source metal layer. A first photoresist pattern is formed by
patterning the photoresist film. The first photoresist pattern
includes a source electrode/line region having a first thickness, a
drain electrode region having the first thickness, and a channel
forming region having a second thickness. The second thickness is
thinner than the first thickness. A data line and a channel portion
are formed by etching the source metal layer and the active layer
using the first photoresist pattern as a mask. A second photoresist
pattern is formed by removing the channel forming portion of the
first photoresist pattern, and the second photoresist pattern
exposes a portion of the source metal layer. A source electrode and
a drain electrode are formed by etching the source metal layer
using the second photoresist pattern as a mask, and an ohmic
contact pattern is formed by etching the active layer using the
second photoresist pattern as a mask. A pixel electrode is formed
on the base substrate having the drain electrode. The pixel
electrode is connected to the drain electrode.
It is to be understood that both the foregoing general description
and the following detailed description are exemplary and
explanatory and are intended to provide further explanation of the
invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to provide a further
understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention, and together with the description serve to explain
the principles of the invention.
FIG. 1 is a plan view showing an array substrate according to an
exemplary embodiment of the present invention.
FIG. 2, FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, and FIG. 8 are
cross-sectional views showing a method of manufacturing the array
substrate of FIG. 1.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
The invention is described more fully hereinafter with reference to
the accompanying drawings, in which embodiments of the invention
are shown. This invention may, however, be embodied in many
different forms and should not be construed as limited to the
embodiments set forth herein. Rather, these embodiments are
provided so that this disclosure will be thorough and complete, and
will fully convey the scope of the invention to those skilled in
the art. In the drawings, the size and relative sizes of layers and
regions may be exaggerated for clarity.
It will be understood that when an element or layer is referred to
as being "on," "connected to," or "coupled to" another element or
layer, it can be directly on, connected or coupled to the other
element or layer or intervening elements or layers may be present.
In contrast, when an element is referred to as being "directly on,"
"directly connected to," or "directly coupled to" another element
or layer, there are no intervening elements or layers present. Like
numbers refer to like elements throughout. As used herein, the term
"and/or" includes any and all combinations of one or more of the
associated listed items.
It will be understood that, although the terms first, second,
third, etc. may be used herein to describe various elements,
components, regions, layers, and/or sections, these elements,
components, regions, layers, and/or sections should not be limited
by these terms. These terms are only used to distinguish one
element, component, region, layer, or section from another region,
layer, or section.
Spatially relative terms, such as "beneath," "below," "lower,"
"above," "upper," and the like, may be used herein for ease of
description to describe one element or feature's relationship to
another element(s) or feature(s) as illustrated in the figures. It
will be understood that the spatially relative terms are intended
to encompass different orientations of the device in use or
operation in addition to the orientation depicted in the figures.
For example, if the device in the figures is turned over, elements
described as "below" or "beneath" other elements or features would
then be oriented "above" the other elements or features. Thus, the
exemplary term "below" can encompass both an orientation of above
and below. The device may be otherwise oriented (rotated 90 degrees
or at other orientations) and the spatially relative descriptors
used herein interpreted accordingly.
The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a," "an," and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
Embodiments of the invention are described herein with reference to
cross-section illustrations that are schematic illustrations of
idealized embodiments (and intermediate structures) of the
invention. As such, variations from the shapes of the illustrations
as a result, for example, of manufacturing techniques and/or
tolerances, are to be expected. Thus, embodiments of the invention
should not be construed as limited to the particular shapes of
regions illustrated herein but are to include deviations in shapes
that result, for example, from manufacturing. For example, an
implanted region illustrated as a rectangle will, typically, have
rounded or curved features and/or a gradient of implant
concentration at its edges rather than a binary change from
implanted to non-implanted region. Likewise, a buried region formed
by implantation may result in some implantation in the region
between the buried region and the surface through which the
implantation takes place. Thus, the regions illustrated in the
figures are schematic in nature and their shapes are not intended
to illustrate the actual shape of a region of a device and are not
intended to limit the scope of the invention.
Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and will not be
interpreted in an idealized or overly formal sense unless expressly
so defined herein.
Photoresist Composition
A photoresist composition according to an exemplary embodiment of
the present invention includes a binder resin, a photo acid
generator, an acryl resin represented by Chemical Formula 1, and a
solvent.
##STR00002##
In Chemical Formula 1, R.sub.1, R.sub.2, R.sub.3, R.sub.4, and
R.sub.5 each represent a hydrogen atom or an alkyl group having 1-4
carbon atoms, and a, b, d, and e each represent a value in a range
of about 0.01 to about 0.99, and the sum of a, b, d, and e is
1.
Hereinafter, components of the photoresist composition according to
an exemplary embodiment of the present invention will be
described.
The binder resin may be soluble in an alkali solution. For example,
the binder resin may be prepared by reacting a phenol compound with
an aldehyde compound in the presence of an acidic catalyst. A
content of the binder resin may be about 1% to about 50% by weight
of the photoresist composition.
Examples of the phenol compound may include phenol, o-cresol,
m-cresol, p-cresol, 2,3-dimethylphenol, 3,4-dimethylphenol,
3,5-dimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol,
2,3,6-trimethylphenol, 2-t-butylphenol, 3-t-butylphenol,
4-t-butylphenol, 2-methylresorcinol, 4-methylresorcinol,
5-methylresorcinol, 4-t-butylcatechol, 2-methoxyphenol,
3-methoxyphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol,
2-isopropylphenol, 2-methoxy-5-methylphenol,
2-t-butyl-5-methylphenol, thymol, and isothymol. These may be used
alone or in combinations. In some exemplary embodiments of the
present invention, a mixture of m-cresol and p-cresol may be used
as the phenol compound to control the sensitivity of the
photoresist composition. In one exemplary embodiment, a weight
ratio of m-cresol to p-cresol may be in a range of about 80:20 to
about 20:80. In another exemplary embodiment, the weight ratio may
be in a range of about 70:30 to about 50:50.
Examples of the aldehyde compound may include formaldehyde,
formalin, p-formaldehyde, trioxane, acetaldehyde, benzaldehyde,
phenylacetaldehyde, .alpha.-phenylpropylaldehyde,
.beta.-phenylpropylaldehyde, o-hydroxybenzaldehyde,
m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-chlorobenzaldehyde,
m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-methylbenzaldehyde,
m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde,
p-n-butylbenzaldehyde, and terephthalic acid aldehyde. These may be
used alone or in combinations.
When the content of the binder resin includes less than about 1% by
weight of the photoresist composition, the viscosity of the
photoresist composition may be excessively low such that the
photoresist composition does not form a fine photoresist pattern
having a designated thickness. When the content of the binder resin
is greater than about 50% by weight of photoresist composition, the
viscosity of the photoresist composition may be excessively high
such that the photoresist composition may not be coated on a
substrate. Thus, in some exemplary embodiments, the content of the
binder resin may be about 1% to about 50% by weight of the
photoresist composition.
The photo acid generator is provided with light to generate an
acid, such as Bronsted acid or Lewis acid. Examples of the photo
acid generator may include an onium salt, a halogenated organic
compound, a quinone diazide compound, a bis(sulfonyl)diazomethane
compound, a sulfone compound, an organic acid-ester compound, an
organic acid-amide compound, and an organic acid-imide compound.
These may be used alone or in combinations.
Examples of the onium compound may include a diazonium salt, an
ammonium salt, an iodonium salt (e.g., diphenyliodonium triflate),
a sulfonium salt (e.g., triphenylsulfonium triflate), a phosphonium
salt, an arsonium salt, and an oxonium salt. These may be used
alone or in combinations.
Examples of the halogenated organic compound may include a
halogen-containing oxadiazole compound, a halogen-containing
triazine compound, a halogen-containing triazine compound, a
halogen-containing acetophenone compound, a halogen-containing
benzophenone compound, a halogen-containing sulfoxide compound, a
halogen-containing sulfonic compound, a halogen-containing thiazole
compound, a halogen-containing oxazole compound, a
halogen-containing triazole compound, a halogen-containing 2-pyrone
compound, a halogen-containing heterocyclic compound, a
halogen-containing aliphatic hydrocarbon, a halogen-containing
aromatic hydrocarbon, and a sulfenyl halide compound. These may be
used alone or in combinations.
Particularly, examples of the halogenated organic compound may
include tris(2,3-dibromopropyl)phosphate,
tris(2,3-dibromo-3-chloropropyl)phosphate, tetrabromochlorobutane,
2-[2-(3,4-dimethoxyphenyl)ethenyl]-4,6-bis(trichloromethyl)-S-triazine,
hexachlorobenzene, hexabromobenzene, hexabromocyclododecane,
hexabromocyclododecene, hexabromobiphenyl,
allyltribromophenylether, tetrachlorobisphenol A,
tetrabromobisphenol A, bis(chloroethyl)ether of
tetrachlorobisphenol A, tetrachlorobisphenol S, tetrabromobisphenol
S, bis(2,3-dichloropropyl)ether of tetrachlorobisphenol A,
bis(2,3-dibromopropyl)ether of tetrabromobisphenol A,
bis(chloroethyl)ether of tetrachlorobisphenol S,
bis(bromoethyl)ether of tetrabromobisphenol S,
bis(2,3-dichloropropyl)ether of bisphenol S,
bis(2,3-dibromopropyl)ether of bisphenol S,
tris(2,3-dibromopropyl)isocyanurate,
2,2-bis(4-hydroxy-3,5-dibromophenyl)propane,
2,2-bis(4-(2-hydroxyethoxy)-3,5-dibromophenyl)propane,
dichlorodiphenyltrichloroethane, pentachlorophenol,
2,4,6-trichlorophenyl-4-nitrophenylether,
4,5,6,7-tetrachlorophthalide, 1,1-bis(4-chlorophenyl)ethanol,
1,1-bis(4-chlorophenyl)-2,2,2-trichloroethanol,
2,4,4',5-tetrachlorodiphenylsulfide, and
2,4,4',5-tetrachlorodiphenylsulfone. These may be used alone or in
combinations.
Examples of the quinone diazide compound may include a sulfonic
acid ester of a quinone diazide derivative such as
1,2-benzoquinonediazide-4-sulfonic acid ester,
1,2-naphthoquinonediazide-4-sulfonic acid ester, a sulfonic acid
chloride of a quinone diazide derivative such as
1,2-benzoquinone-2-diazide-4-sulfonic acid chloride,
1,2-naphthoquinone-2-diazide-4-sulfonic acid chloride,
1,2-naphthoquinone-2-diazide-5-sulfonic acid chloride,
1,2-naphthoquinone-1-diazide-6-sulfonic acid chloride, or
1,2-benzoquinone-1-diazide-5-sulfonic acid chloride. These may be
used alone or in combinations.
Examples of the bis(sulfonyl)diazomethane compound may include
.alpha.,.alpha.'-bis(sulfonyl)diazomethane containing an alkyl
group, an alkenyl group, an aralkyl group, an aromatic group, and a
heterocyclic group, which may be symmetrically substituted,
non-symmetrically substituted, or unsubstituted. These may be used
alone or in combinations.
Examples of the sulfone compound may include a sulfone compound and
a disulfone compound, which contains an alkyl group, an alkenyl
group, an aralkyl group, an aromatic group, and a heterocyclic
group, which may be symmetrically substituted, non-symmetrically
substituted, or unsubstituted. These may be used alone or in
combinations.
Examples of the organic acid ester may include carboxylic acid
ester, sulfonic acid ester, and phosphoric acid ester. Examples of
the organic acid amide may include carboxylic acid amide, sulfonic
acid amide, and phosphoric acid amide. Examples of the organic acid
imide may include carboxylic acid imide, sulfonic acid imide, and
phosphoric acid imide. These may be used alone or in
combinations.
Moreover, examples of the photo acid generator may further include
cyclohexylmethyl(2-oxocyclohexyl)sulfonium trifluoromethane
sulfonate, dicyclohexylmethyl(2-oxocyclohexyl)sulfonium
trifluoromethane sulfonate, 2-oxocyclohexyl(2-norbornyl)sulfonium
trifluoromethane sulfonate, 2-cyclohexylsulfonylcyclohexanone,
dimethyl(2-oxocyclohexyl)sulfonium trifluoromethane sulfonate,
triphenylsulfonium trifluoromethane sulfonate, diphenyliodonium
trifluoromethane sulfonate, N-hydroxysuccinimidyl trifluoromethane
sulfonate, phenyl p-toluene sulfonate, and
.alpha.-carbonyl-.alpha.-sulfonyldiazomethane containing an alkyl
group, an alkenyl group, an aralkyl group, an aromatic group, or a
heterocyclic group, which may be symmetrically substituted,
non-symmetrically substituted, or unsubstituted. These may be used
alone or in combinations.
When a content of the photo acid generator is less than about 1% by
weight of the photoresist composition, a photoresist pattern formed
from the photoresist composition may not be clear since the amount
of acid generated by light exposure may not be sufficient. When the
content of the photo acid generator is greater than about 20% by
weight of the photoresist composition, a photoresist pattern formed
from the photoresist composition may have a round edge or may be
damaged in the course of a development process. Thus, in some
exemplary embodiments, the content of the photo acid generator may
be about 1% to about 20% by weight of the photoresist
composition.
The acryl resin represented by Chemical Formula 1 may be prepared
by copolymerizing four different types of monomers.
For example, R.sub.1, R.sub.2, R.sub.3, R.sub.4, and R.sub.5 in
Chemical Formula 1 may each represent any one of a hydrogen atom, a
methyl group, an ethyl group, a butyl group, and a propyl
group.
Each of a, b, d, and e represent a value in a range of about 0.01
to about 0.99, and the sum of a, b, d, and e is 1. For example, in
Chemical Formula 1, a may be about 0.5 to about 0.6, b may be about
0.25 to 0.35, d may be about 0.05 to about 0.15, and e may be about
0.01 to about 0.1.
In one exemplary embodiment, the acryl resin may be represented by
the following Chemical Formula 2.
##STR00003##
When the content of the acryl resin is less than about 1% by weight
of the photoresist composition, the acryl resin may not improve the
exposure margins and the thermal resistance of the photoresist
pattern formed using the photoresist composition. When the content
of the acryl resin is greater than about 20% by weight of the
photoresist composition, the adhesion of the photoresist pattern
and the substrate may be low and a residual pattern of the
photoresist pattern may not be formed on the substrate. Thus, in
some exemplary embodiments, the content of the acryl resin may be
about 1% to about 20% by weight of the photoresist composition.
A weight average molecular weight of the acryl resin may be about
5,000 to 30,000. The weight average molecular weight denotes a
polystyrene-reduced weight-average molecular weight measured by gel
permeation chromatography (GPC). When the weight average molecular
weight of the acryl resin is less than about 5,000, the acryl resin
may not improve the exposure margins and the thermal resistance of
the photoresist pattern. When the weight average molecular weight
of the acryl resin is greater than about 30,000, the acryl resin
may be not soluble in the solvent. In exemplary embodiments, the
weight average molecular weight of the acryl resin may be about
16,000.
Examples of the solvent may include alcohols such as methanol and
ethanol, ethers such as tetrahydrofurane, glycol ethers such as
ethylene glycol monomethyl ether and ethylene glycol monoethyl
ether, ethylene glycol alkyl ether acetates such as methyl
cellosolve acetate and ethyl cellosolve acetate, diethylene glycols
such as diethylene glycol monomethyl ether, diethylene glycol
monoethyl ether, and diethylene glycol dimethyl ether, propylene
glycol monoalkyl ethers such as propylene glycol methyl ether,
propylene glycol ethyl ether, propylene glycol propyl ether, and
propylene glycol butyl ether, propylene glycol alkyl ether acetates
such as propylene glycol methyl ether acetate, propylene glycol
ethyl ether acetate, propylene glycol propyl ether acetate, and
propylene glycol butyl ether acetate, propylene glycol alkyl ether
propionates such as propylene glycol methyl ether propionate,
propylene glycol ethyl ether propionate, propylene glycol propyl
ether propionate, and propylene glycol butyl ether propionate,
aromatic compounds such as toluene and xylene, ketones such as
methyl ethyl ketone, cyclohexanone, and
4-hydroxy-4-methyl-2-pentanone, and ester compounds such as methyl
acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl
2-hydroxypropionate, methyl 2-hydroxy-2-methyl propionate, ethyl
2-hydroxy-2-methyl propionate, methyl hydroxyacetate, ethyl
hydroxyacetate, butyl hydroxyacetate, methyl lactate, ethyl
lactate, propyl lactate sulfate, butyl lactate, methyl
3-hydroxypropionate, ethyl 3-hydroxypropionate, propyl
3-hydroxypropionate, butyl 3-hydroxypropionate, methyl
2-hydroxy-3-methyl butanoate, methyl methoxy acetate, ethyl methoxy
acetate, propyl methoxy acetate, butyl methoxy acetate, methyl
ethoxy acetate, ethyl ethoxy acetate, propyl ethoxy acetate, butyl
ethoxy acetate, methyl propoxy acetate, ethyl propoxy acetate,
propyl propoxy acetate, butyl propoxy acetate, methyl butoxy
acetate, ethyl butoxy acetate, propyl butoxy acetate, butyl butoxy
acetate, methyl 2-methoxypropionate, ethyl 2-methoxypropionate,
propyl 2-methoxypropionate, butyl 2-methoxypropionate, methyl
2-ethoxypropionate, ethyl 2-ethoxypropionate, propyl
2-ethoxypropionate, butyl 2-ethoxypropionate, methyl
2-butoxypropionate, ethyl 2-butoxypropionate, propyl
2-butoxypropionate, butyl 2-butoxypropionate, methyl
3-methoxypropionate, ethyl 3-methoxypropionate, propyl
3-methoxypropionate, butyl 3-methoxypropionate, methyl
3-ethoxypropionate, ethyl 3-ethoxypropionate, propyl
3-ethoxypropionate, butyl 3-ethoxypropionate, methyl
3-propoxypropionate, ethyl 3-propoxypropionate, propyl
3-propoxypropionate, butyl 3-propoxypropionate, methyl
3-butoxypropionate, ethyl 3-butoxypropionate, propyl
3-butoxypropionate, and butyl 3-butoxypropionate. These may be used
alone or in combinations.
In some exemplary embodiments, the photoresist composition may
further include a hydroxyl phenol derivative represented by
Chemical Formula 3.
##STR00004##
In Chemical Formula 1, R.sub.6, R.sub.7, and R.sub.8 each represent
an alkyl group having 1-3 carbon atoms. R.sub.6, R.sub.7, and
R.sub.8 may include a methyl group, an ethyl group, and a propyl
group. In one exemplary embodiment, R.sub.6, R.sub.7, and R.sub.8
may each represent a methyl group.
If the photoresist composition further includes a hydroxyl phenol
derivative, the exposure margins and the thermal resistance of the
photoresist pattern may be more improved.
When the content of the hydroxyl phenol derivative is less than
about 1% by weight of the photoresist composition, the hydroxyl
phenol derivative may not improve the exposure margins and the
thermal resistance of the photoresist pattern. When the content of
the hydroxyl phenol derivative is greater than about 10% by weight
of the photoresist composition, the content of the binder resin and
the acryl resin is relatively small so that control of the exposure
margins and a shape control of the photoresist pattern may be
difficult. Thus, in exemplary embodiments, the content of the
hydroxyl phenol derivative may be about 1% to about 10% by weight
of the photoresist composition.
In addition, in some exemplary embodiments, the photoresist
composition further includes additives such as an adhesion
promotion agent, a surfactant, an acid diffusion suppressant, and a
dye. The content of the additives may be about 1% to about 10% by
weight of the photoresist composition.
The adhesion promotion agent may improve an adhesion between a
substrate and a photoresist pattern formed from the photoresist
composition. Examples of the adhesion promotion agent may include a
silane coupling agent containing a reactive substitution group such
as a carboxyl group, a methacrylic group, an isocyanate group, or
an epoxy group. Particularly, examples of the silane coupling agent
may include .gamma.-methacryloxypropyl trimethoxy silane, vinyl
triacetoxy silane, vinyl trimethoxy silane, .gamma.-isocyanate
propyl triethoxy silane, .gamma.-glycidoxy propyl trimethoxy
silane, and .beta.-(3,4-epoxy cyclohexyl)ethyl trimethoxy silane.
These may be used alone or in combinations.
The surfactant may improve coating characteristics and development
characteristics of the photoresist composition. Examples of the
surfactant may include polyoxyethylene octylphenylether,
polyoxyethylene nonylphenylether, F171, F172, F173 (trade name,
manufactured by Dainippon Ink in Japan), FC430, FC431 (trade name,
manufactured by Sumitomo 3M in Japan), and KP341 (trade name,
manufactured by Shin-Etsu Chemical in Japan). These may be used
alone or in combinations.
The acid diffusion suppressant may prevent an acid from diffusing
into an area that is not exposed to light. Examples of the
photosensitizer may include an amine, ammonium hydroxide, and a
photosensitive base. Particularly, examples of acid diffusion
suppressant may include tetrabutylammonium hydroxide,
triethanolamine, diethanolamine, trioctylamine, n-octylamine,
trimethylsulfonium hydroxide, and triphenylsulfonium hydroxide.
These may be used alone or in combinations.
The dye may serve to control the contrast of a photoresist pattern.
The dye may be selected in view of solubility and heat resistance.
Examples of the dye may include a pyrazoleazo-based dye, an
anilinoazo-based dye, an arylazo-based dye, a
triphenylmethane-based dye, an anthraquinone-based dye, an
anthrapyridone-based dye, a benzylidene-based dye, an oxonol-based
dye, a pyrazoletriazoleazo-based dye, a pyridoneazo-based dye, a
cyanine-based dye, a phenothiazine-based dye, a
pyrrolopyrazoleazomethine-based dye, a xanthene-based dye, a
phthalocyanine-based dye, a benzopyran-based dye, and an
indigo-based dye. These may be used alone or in combinations.
According to the above, a photoresist composition may not be
affected as much by changes in the depth of focus (DOF) of an
optical system. The DOF may be defined by a distance capable of
forming a fine photoresist pattern, the distance between the
optical system of the exposure device and the substrate. This
increases a range of forming a fine photoresist pattern. Although a
distance between the optical system of an exposure device and a
substrate changes so the focus of the optical system changes, the
photoresist composition may still form a fine photoresist pattern.
Therefore, forming a photoresist pattern using the photoresist
composition may not be affected by the focus of the optical system,
which may vary due to physical factors such as the manufacturing
precision of a stage supporting the substrate, vibrations when
transferring the substrate, and manufacturing errors in the optical
system of the exposure device. Thus, the exposure margins of the
photoresist pattern may be improved.
Furthermore, the thermal resistance of the photoresist pattern may
be improved, and the reliability of manufacturing a thin-film
transistor (TFT) by the four-mask process may be improved.
Hereinafter, a method of manufacturing an array substrate according
to an exemplary embodiment of the present invention will be
described more fully with reference to the accompanying
drawings.
Method of Manufacturing an Array Substrate
FIG. 1 is a plan view showing an array substrate according to an
exemplary embodiment of the present invention. FIG. 2, FIG. 3, FIG.
4, FIG. 5, FIG. 6, FIG. 7, and FIG. 8 are cross-sectional views
showing a method of manufacturing the array substrate of FIG. 1.
Particularly, FIG. 2, FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, and
FIG. 8 respectively show a cross-section taken along line I-I' of
FIG. 1.
Referring to FIG. 1 and FIG. 2, a gate metal layer (not shown) is
formed on a base substrate 110, and then the gate metal layer is
patterned through a photolithography process using a first exposure
mask (not shown) to form a gate pattern 120.
The gate pattern 120 includes a gate line 122 and a gate electrode
124 connected to the gate line 122. The gate line 122 may extend in
one direction on the base substrate 110, and a plurality of the
gate lines 122 may be arranged parallel to each other. The gate
electrode 124 is connected to the gate line 122 and serves as a
gate terminal of a TFT for a switching device formed in a pixel
P.
The base substrate 110 may be a transparent insulation substrate.
An example of a material that may be used for the base substrate
110 is glass.
For example, the gate metal layer may be formed by a sputtering
process on the base substrate 110. The gate pattern 120 may be
formed by wet etching process. Examples of a material that may be
used for the gate pattern 120 may include aluminum (Al), molybdenum
(Mo), neodymium (Nd), chromium (Cr), tantalum (Ta), titanium (Ti),
tungsten (W), copper (Cu), silver (Ag), or an alloy thereof. The
gate pattern 120 may have a double-layer structure including at
least two metal layers having different physical characteristics.
For example, the gate pattern 120 may have an Al/Mo double-layer
structure including an Al layer and a Mo layer so as to reduce
resistance.
Referring to FIG. 3, a gate insulation layer 130 and an active
layer 140 are sequentially formed on the base substrate 110 having
the gate pattern 120. The gate insulation layer 130 and the active
layer 140 may be formed by plasma-enhanced chemical vapor
deposition (PECVD) in one exemplary embodiment.
The gate insulation layer 130 may protect and insulate the gate
pattern 120. Examples of a material that may be used for the gate
insulation layer 130 may include silicon nitride and silicon oxide.
For example, a thickness of the gate insulation layer 130 may be
about 4,500 .ANG..
The active layer 140 includes a semiconductor layer 142 and an
ohmic contact layer 144. An example of a material that may be used
for the semiconductor layer 142 may is amorphous silicon, and an
examples of a material that may be used for the ohmic contact layer
144 is amorphous silicon into which n.sup.+ impurities are
implanted at a high concentration.
A source metal layer 150 is formed on the active layer 140. In one
example, the source metal layer 150 may have a Mo/Al/Mo
triple-layer structure to reduce the resistance of the source metal
layer 150. Alternatively, the source metal layer 150 may have a
single layer including Mo or Al.
Referring to FIG. 4, a photoresist composition is coated on the
source metal layer 150 to form a photoresist film (not shown). The
photoresist film is exposed to light by a second exposure mask (not
shown), such as a slit mask or a halftone mask, and then developed
to form a first photoresist pattern 160.
The photoresist composition includes a binder resin, a photo acid
generator, an acryl resin represented by Chemical Formula 1, and a
solvent.
##STR00005##
In Chemical Formula 1, R.sub.1, R.sub.2, R.sub.3, R.sub.4, and
R.sub.5 each represent a hydrogen atom or an alkyl group having 1-4
carbon atoms, and a, b, d, and e each represent a value in a range
of about 0.01 to about 0.99, and the sum of a, b, d, and e is
1.
The photoresist composition is substantially the same composition
as in exemplary embodiments of the present invention described
above. Thus, any further description will be omitted.
The first photoresist pattern 160 includes a source electrode/line
region having a first thickness, a drain electrode region having
the first thickness, and a channel forming region having a second
thickness. The channel forming region is formed on a channel
forming area CR of the base substrate 110. The second thickness is
thinner than the first thickness. The channel forming region of the
first photoresist pattern 160 is formed by partially exposing light
through a slit portion or a halftone portion of the first exposure
mask. After the source metal layer 150 is etched using the first
photoresist pattern 160, a remaining source metal layer forms a
source electrode (157, see FIG. 7) and a source line (155, see FIG.
5) under the source electrode/line region of the first photoresist
pattern 160 and a drain electrode (158, see FIG. 7) under the drain
electrode region of the first photoresist pattern 160.
Referring to FIG. 1 and FIG. 5, the source metal layer 150 is
etched using the first photoresist pattern as etching preventing
layer. For example, the source metal layer 150 may be etched by a
wet etching process.
After the source metal layer 150 is etched by the wet etching
process using the first photoresist pattern 160, the source line
155 and a source/drain metal pattern 156 remain on the base
substrate 110. The source line 155 may extend parallel to the gate
line 122 on the base substrate 110, and a plurality of the source
lines 155 may be arranged parallel each other. Since the source
metal layer 150 is etched by the wet etching process, an edge of
the source line 155 and an edge of the source/drain metal pattern
156 may coincide with an edge of the first photoresist pattern 160
to form an undercut having a width .DELTA.d.
Thereafter, the active layer 140 is etched using the first
photoresist pattern 160 as an etching prevention mask. For example,
the active layer 140 may be etched by a dry etching process. After
the active layer 140 is etched, a remaining semiconductor layer 142
forms a channel portion (146, see FIG. 7) and a remaining ohmic
contact layer 144 forms a pair of ohmic contact patterns (148, see
FIG. 7).
Referring to FIG. 5 and FIG. 6, a second photoresist pattern 162 is
formed by removing the channel forming region forming on the
channel forming area CR. Thus, the source/drain metal pattern 156
forming on the channel forming area CR is exposed through the
second photoresist pattern 162.
Alternatively, the active layer 140 may be etched after the second
photoresist pattern 162 is formed. Thus, the active layer 140 may
be etched using the source/drain metal pattern 156 and the second
photoresist pattern 162 as an etching prevention mask.
Referring to FIG. 1 and FIG. 7, the source electrode 157 and the
drain electrode 158 are formed by etching the source/drain metal
pattern 156 formed on the channel forming area CR and exposed
through the second photoresist pattern 162. For example, the
source/drain metal pattern 156 may be etched by a wet etching
process.
The source electrode 157 is connected to the source line 155, and
serves as a source terminal of the TFT. The drain electrode 158 is
spaced apart from the source electrode 157 and serves as a drain
terminal of the TFT.
Thereafter, an exposed portion of the ohmic contact layer 144 is
etched using the second photoresist pattern 162 as a mask to form a
pair of ohmic contact patterns 148. The exposed portion of the
ohmic contact layer 144 is a portion of the ohmic contact layer 144
formed on the channel forming area CR of the base substrate 110.
The ohmic contact patterns 148 are spaced apart from each other.
The second photoresist pattern 162 is removed from the base
substrate 110. For example, the second photoresist pattern 162 may
be removed by a stripping process using a stripping solution. Thus,
the TFT having a channel is formed on the base substrate 110. The
channel may be a portion between the source electrode 157 and the
drain electrode 158, and the channel is formed on the channel
forming area CR of the base substrate 110.
Referring to FIG. 1 and FIG. 8, a passivation layer 170 is formed
on the base substrate 110 having the TFT. The passivation layer 170
protects and insulates the TFT and the data line 155. Examples of a
material that may be used for the passivation layer 170 may include
silicon nitride, silicon oxide, etc. For, example, the passivation
layer 170 may be formed through a chemical vapor deposition (CVD)
method, and a thickness of the passivation layer 170 may be about
500 .ANG. to about 2,000 .ANG..
The passivation layer 170 is patterned through a photolithography
process using a third exposure mask (not shown) to form a contact
hole 172 exposing a portion of the drain electrode 158.
After the contact hole 172 is formed, a transparent conductive
layer is formed on the passivation layer 170. The transparent
conductive layer is patterned through a photolithography process
using a fourth exposure mask (not shown) to form a pixel electrode
180 in the pixel P. The pixel electrode 180 is connected to the
drain electrode 158 through the contact hole 172. Examples of a
material that may be used for the pixel electrode 180 may include
indium zinc oxide (IZO) and indium tin oxide (ITO).
Alternatively, before the pixel electrode 180 is formed, an organic
insulation layer (not shown) may be formed on the passivation layer
170 to planarize the base substrate 110.
The photoresist composition and the method of manufacturing an
array substrate according to exemplary embodiments of the present
invention will be further described hereinafter through Examples
and Comparative Examples.
Preparation of a Photoresist Composition
Example 1
A phenol mixture including m-cresol and p-cresol in a weight ratio
of about 50:50 was reacted with formaldehyde to prepare a novolak
resin as a binder resin, of which a weight average molecular weight
was about 8,000. About 2% by weight of an acryl resin represented
by Chemical Formula 3, about 8% by weight of the binder resin,
about 5% by weight of 1,2-naphtoquinondiazide-4-sufonic ester as a
photo acid generator, and about 85% by weight of propylene glycol
methyl ether acetate as a solvent were mixed with each other to
prepare a photoresist composition.
##STR00006##
Example 2
A phenol mixture including m-cresol and p-cresol in a weight ration
of about 50:50 was reacted with formaldehyde to prepare a novolak
resin as a binder resin, of which a weight average molecular weight
was about 8,000. About 2% by weight of an acryl resin represented
by Chemical Formula 3, about 2% by weight of a hydroxyl phenol
derivate represented by Chemical Formula 4, about 8% by weight of
the binder resin, about 5% by weight of
1,2-naphtoquinondiazide-4-sufonic ester as a photo acid generator,
and about 83% by weight of propylene glycol methyl ether acetate as
a solvent were mixed with each other to prepare a photoresist
composition.
##STR00007##
Comparative Example 1
A phenol mixture including m-cresol and p-cresol in a weight ration
of about 50:50 was reacted with formaldehyde to prepare a novolak
resin as a binder resin, of which a weight average molecular weight
was about 8,000. About 10% by weight of the binder resin, about 5%
by weight of 1,2-naphtoquinondiazide-4-sufonic ester as a photo
acid generator, and about 85% by weight of propylene glycol methyl
ether acetate as a solvent were mixed with each other to prepare a
photoresist composition.
Evaluation of a photoresist pattern formed using a photoresist
composition
The compositions prepared in Examples 1 and 2 and Comparative
Example 1 were each spread on a substrate to form a photoresist
film. A mask was disposed on the photoresist film, and the
photoresist film was exposed by ultra violet light in changing
focus of an optical system of an exposure device.
After an exposed photoresist film was developed using an alkali
solution and baked on high temperature so that a photoresist
pattern was formed on the substrate, a shape of the photoresist
pattern was observed through an electron microscope. The obtained
results are shown in Table 1 and Table 2.
TABLE-US-00001 TABLE 1 Depth of Focus (DOF) Example 1 About 20
.mu.m Example 2 About 25 .mu.m Comparative Example 1 About 15
.mu.m
TABLE-US-00002 TABLE 2 Breakdown temperature of a photoresist
pattern Example 1 Over about 130.degree. C. Example 2 Over about
135.degree. C. Comparative Example 1 Over about 120.degree. C.
The DOF may be defined by a distance capable of forming a fine
photoresist pattern, the distance between the optical system of the
exposure device and the substrate. In Table 1, the DOF represents a
maximum of the distance.
Referring to Table 1, a DOF of the photoresist pattern according to
Example 1 is about 20 .mu.m, a DOF of the photoresist pattern
according to Example 2 is about 25 .mu.m, and a DOF of the
photoresist pattern according to Comparative Example 1 is about 15
.mu.m. Although a focus of the optical system is changed, the range
of forming the fine photoresist pattern is wide. Therefore, forming
the photoresist pattern including the photoresist composition may
not depend on the focus of the optical system, which is changed by
physical factors such as the manufacturing precision of a stage
supporting the substrate, vibrations when transferring the
substrate, and manufacturing errors of the optical system of the
exposure device.
Referring to Table 2, a breakdown temperature of a photoresist
pattern according to Example 1, which includes the acryl resin
represented by Chemical Formula 3, is higher than a breakdown
temperature of a photoresist pattern according to Comparative
Example 1, which does not include the acryl resin. In other words,
a thermal resistance of the photoresist pattern according to
Example 1 is better than a thermal resistance of the photoresist
pattern according to Comparative Example 1.
Moreover, a breakdown temperature of a photoresist pattern
according to Example 2, which further includes the hydroxyl phenol
derivative represented by Chemical Formula 4, is higher than the
breakdown temperatures of the photoresist patterns according to
Example 1 and Comparative Example 1.
It will be apparent to those skilled in the art that various
modifications and variation can be made in the present invention
without departing from the spirit or scope of the invention. Thus,
it is intended that the present invention cover the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
* * * * *